Many systems and architectures have been disclosed for handling data traffic over distributed networks. Today's Metro Ethernet Networks (MEN) are implemented utilizing IEEE 802.1ad Provider Bridges (PBs). Each PB provides separation for the customer Virtual Local Area Network (VLAN) space and the provider VLAN space by distinguishing a Customer VLAN (C-VLAN) and a Service VLAN (S-VLAN). Provider Edge Bridges (PEBs) in the PB-based VLAN add an S-VLAN tag into the header of customer frames entering the provider network. PB Networks achieve provider/customer service separation since the S-VLAN is used for service identification and forwarding, but customer addresses are still visible in the provider network. MEN operators may upgrade their networks in order to avoid these limitations of PBs.
The natural evolution and upgrade of a PB network is the deployment of IEEE 802.1ah Provider Backbone Bridges (PBBs). PBB is a set of architecture and protocols for routing of customer traffic of a customer network over a provider's network allowing interconnection of multiple PB networks without losing each customer's individually defined VLANs. Thus, PBB provides a cost-efficient way to address customer number scalability issues, as it allows edge port upgrades for services associated with large numbers of customers. Thus, a PB-based PEB can be upgraded to a PBB-based Backbone Edge Bridge (BEB) to provide service scalability. BEBs implement a full encapsulation on customer frames by adding a new header that includes the backbone destination address, the backbone source address, the Backbone VLAN (B-VLAN), and a Service Instance Tag (I-tag) that contains a Backbone Service Instance Identifier (I-SID) used as a service identifier. Thus, by means of MAC-in-MAC (Media Access Control) encapsulation, the PBB separates customer and provider MAC address space and resolves the service scalability limitations through the introduction of the I-SID. It is noted here that core bridges of a PB Network (PBN) remain untouched, as no upgrade is needed for PBB transport.
Alternatively, a PB MEN may be upgraded such that Internet Protocol/Multiprotocol Label Switching (IP/MPLS) is deployed and the PEBs are replaced with IP/MPLS Provider Edge (PE) routers. The transport between the PE routers utilizes the existing PB network, at least in the first phase of the migration to the new technology. The IP/MPLS PE routers provide Layer 2 (i.e., the Ethernet layer) service by using Virtual Private LAN Service (VPLS) or Virtual Private Wire Service (VPWS). The upgrade of PB-based edge bridges in this case may mean deployment of new edge nodes that implement IP/MPLS.
Edge bridges of the PB network may implement a hot upgrade capability for the introduction of new features under PBB or IP/MPLS. After the deployment of new features, PB-based VLANs are migrated to the new technology. Nevertheless, a VLAN service is typically provided by multiple edge nodes—by two edge nodes in case of a point-to-point VLAN and by more edge nodes in case of a multipoint VLAN service. Currently, in order to provide in-service migration of a PB-based VLAN, the VLAN service should be moved from the old technology to the new technology exactly at the same time in all edge nodes supporting the VLAN service. This existing solution is very difficult to implement without additional cost, because it requires coordination and strict timing between the management actions being run on all edge nodes individually. In addition, the existing method is prone to eventual configuration errors. If the configuration operation is unsuccessful in one or more edge nodes, the service is disrupted and it may be difficult to roll back to the original VLAN service configuration to prevent such service disruption.